This randomized trial of mammography reminders to women will occur in an HMO population where an organized screening program regularly mails recommendations to schedule free mammograms, and where adherence to the recommendation can be identified through automated data systems. Only 56% of women get mammograms by one year from the recommendation (participate). Randomized trials have achieved 40% mortality reductions when 85% of the target population obtains the mammogram. More must be done to achieve participation rates which will realize the potential mortality reductions afforded by mammographic screening. A random sample of women due for a mammogram will be identified (n=2,199). Over-sampling will occur among previous non-participants. Prior to getting the routine mammography invitation, a survey will measure constructs based primarily upon the Theory of Reasoned Action. Women who do not schedule an appointment by two months(n= 1,582) will then be randomized to receive one of three communications: 1) a postcard reminding them to schedule; 2) a simple telephone call advising women to schedule, or 3) a personalized telephone call addressing emotional concerns (affect), beliefs about mammography (attitude), logistic considerations (facilitating conditions) and self-perceived risk. Women will be able to schedule appointments at the time of either telephone calf. A follow-up telephone survey will be conducted to allow a process evaluation of the intervention and measure changes in affect, attitude, and self-perceived breast cancer risk. The effect of the intervention will be tested by comparing the proportion in each intervention group who get mammograms during the year subsequent to the original letter of recommendation. Analyses will evaluate factors that predict which women schedule mammograms, which interventions resulted in the most participation, and how intervention effects differed by Theory of Reasoned Action constructs, baseline perceived risk, and previous mammography experience. The study has implications for individual physicians concerned with how to encourage participation at the point of referral, organized screening programs in HMOs, and health educators trying to influence populations.